1. Field of the Invention
The present invention relates to light emitting diode (LED) components and the uses thereof. In particular, the invention concerns LED components with a wide light spectrum and having a specific peak intensity. The use of the present LED components for therapeutic, photosynthesis or photomorphogenetic use, such as in skin, muscle, wound treatments as well as activate other various receptors and chemical and physical reactions in living organisms, is also disclosed. The LED components can be also used for a plant cultivation process such as greenhouse growing or crops' seedlings growth.
2. Description of Related Art
The plants, crops, animals, humans are proven to benefits for certain parts of UV, visible and near infrared (NIR) spectrum. Various chemical substances may absorb the energy of emitted spectrum and use the energy in photochemical, chemical reaction or otherwise physically active cell activity. These reactions are well known in photosynthesis process in plants. However, it is also indicated that certain specific spectra can improve wound healing or activate cell growth.
Artificial lighting for plant cultivation is an important factor, which determines the cost and nutritional quality of greenhouse vegetables. Efficiency of greenhouse lighting has been improved by application of high-pressure sodium (HPS) lamps, which emit predominantly yellowred light effectively absorbed by chlorophylls. The improvement is achieved owing to a high overall light yield and the emission spectrum suitable for plant cultivation. However, application of light sources with a spectrum substantially different from the solar one, encounters difficulties owing to sensitivity of plants to the spectral composition of light. Particularly in HPS lamps designed for horticulture applications, the blue component can be enhanced; however, a further purposeful tailoring of the spectrum in the red wavelength region of the HPS lamps has limitations. In principle, the spectrum can be adjusted using different phosphors, but data on the spectrum optimal for particular plants are still scarce and fragmental and cannot be optimized.
Light-emitting diodes (LEDs) present a versatile alternative for artificial greenhouse lighting with numerous advantages. In comparison with conventional HPS and fluorescent lamps, LEDs are an energy-efficient, environmentally friendly and longevous source of light. Assembling of LEDs, which are already available in the entire relevant spectral range from near infrared (IR) to near ultraviolet (UV), enables one to tailor the spectrum for optimal growth. Particularly the spectra in the red and far-red regions are essential for successful and efficient plant cultivation typically described as 660 nm region wavelengths contributing most for the photosynthesis and 730 nm region wavelengths contributing most for photomorphogenesis in plants. These types of spectra can be obtained by direct electroluminescence from AlGaAs or AlInGaP semiconductor LEDs or using blue emitting high power (HP) LED which blue light is then converted to RED wavelength with phosphors materials.
The application of light therapy with LEDs will significantly improve the medical care that is available to astronauts on long-term space missions based on NASA experiments. LEDs stimulate the basic energy processes in the mitochondria (energy compartments) of each cell, particularly when near-infrared light is used to activate the color sensitive chemicals (chromophores, cytochrome systems) inside. Proposed Optimal LED wavelengths include 680, 730 and 880 nm and those have improved the healing of wounds in laboratory animals. Furthermore, DNA synthesis in fibroblasts and muscle cells has been quintupled using NASA LED light alone, in a single application combining 680, 730 and 880 nm each at 4 Joules per centimeter squared. The light is absorbed by mitochondria where it stimulates energy metabolism in muscle and bone, as well as skin and subcutaneous tissue. Also lasers provide low energy stimulation of tissues which results in increased cellular activity during wound healing including increased fibroblast proliferation, growth factor synthesis, collagen production and angiogenesis. Lasers, however, have some inherent characteristics that make their use in a clinical setting problematic, such as limitations in wavelength capabilities and beam width. The combined wavelengths of light optimal for wound healing cannot be efficiently produced, and the size of wounds that may be treated by lasers is limited. Light-emitting diodes (LEDs) offer an effective alternative to lasers with human and animal populations include treatment of serious burns, crush injuries, non-healing fractures, muscle and bone atrophy, traumatic ischemic wounds, radiation tissue damage, compromised skin grafts, and tissue regeneration.
As known in the art, there are several applications that benefit on the availability efficient and correct spectrum red and far red LEDs. However, producing efficient broad band red and far LEDs devices with optimal spectral emission for various forms of light therapy and plant cultivation is still problematic. In particular the problem arises when broad emission spectrum is beneficial and required at red and/or far red wavelength regions. All phosphorescent materials are sensitive for heat and in particularly so the phosphorescent materials that result in long stokes shift emission. Similarly to phosphorescent materials quantum dot nanoparticles particles such as CdSe—ZnS (core-shell) semiconductor crystals can be used for to produce wavelength conversion shorter wavelengths to higher wavelengths. These wavelength conversion materials are also sensitive for thermal quenching. Alternatively the red and far red emission can be produced by using for example AlGaAS semiconductor LEDs, however, it is known by art that typically these devices in order to be efficient result in relatively narrow emission spectrum with narrow less than 50 nm full width of half maximum.